The purpose of this protocol is to determine in postmenopausal women who are not currently on estrogen replacement therapy (ERT), whether symptoms of mild to moderate depression respond to treatment with an estradiol patch. In postmenopausal women whose mild to moderate depression does not respond to estrogen alone, the protocol will obtain pilot data on the question of whether estrogen treatment facilitates response to sertraline, a serotonergic anti-depressant.